An anti-inflammatory drug currently prescribed for arthritis and pain can prevent formation of precancerous growths in the colon and rectum, two analyses suggest. The drug might be especially valuable for people at high risk of developing these kinds of polyps, the data show.

However, regulatory clearance of the drug, called celecoxib, for cancer prevention is far from assured. Two nearly identical trials began in 1999 and 2001 but were stopped in 2004 when more than the expected number of pa...